Rotary compressor and exhauster.



J. JOHNSTON.

ROTARY COMPRESSOR AND EXHAUSTER.

APPLICATION FILED AUG-23,1916.

Patented Oct. 15, 1918.

w W fl \u /um m i H JOHN JOHNSTON, OF LONDON, ENGLAND.

ROTARY COMPRESSOR AND EXHAUSTER.

Specification of Letters Patent.

Patented Oct. 15, 1918.

Application filed August 23, 1916. Serial No. 116,457.

To all whom it may concern:

Be it known that I, JOHN JOHNSTON, a subject of the King of Great Britain and Ireland, and residing at 1 Victoria street, London, S. W England, have invented certain new and useful Improvements in or Relating to Rotary Compressors and Exhausters, of which the following is a specification.

This invention relates to improvements in rotary compressors and exhausters of the type comprising two drum-like or rotary members mounted one within the other and eccentrically to one another and having an annular liquid piston occupying the space between the members.- 7

One object of the present invention is to provide an improved arrangement of the above type for maintaining the vacuum or compression pressure-produced by the machine at the maximum, while a further object is to devise improvements which shall be particularly suitable for large capacity ma chines of the above type and will obviate the necessity for the very large bearing surfaces which would be required in large capacity machines when constructed in known manner, involving the use of the central shaft as the inlet or outlet for the air or other gas being operated upon by the machine.

With these objects in view the invention consists in a rotary compressor or exhauster of the type referred to provided with a fixed inlet or outlet for the gas being operated upon and having a liquid seal independent of and having no direct connection with the operative liquid of the machine and divided into two parts or portions such that there is produced a difference in the level of the liquid in the two portions due to the centrifugal force balancing the vacuum or compression pressure produced by the machine.

The invention also consists in other details and arrangements hereinafter more particularly referred to.

The accompanying drawing illustrates in sectional elevation one convenient form of device in accordance with the invention.

In carrying my invention into effect in one convenient manner as, for example, in its application to a compressor or exhauster comprising one or more spiral vanes or threads 11 upon the inner rotary member and a shrouding plate 7) upon the outer side or upon each sidc of the thread or spiral vane carrying member as described, for example, in the specification to British Patent No.

227 69 of 1914., I provide an outer drum-like casing 0 and an inner spiral thread carrying member d somewhat after the manner described in the before-mentioned specification, but instead of mounting the inner member cl upon a hollow shaft I mount he same on bearings e surrounding a fixed hollow shaft 7 the inner end of which is formed integral with or has mounted thereon a fixed plate, disk or partition, 9, which latter is located within an annular pocket or chamber it formed in or by the inner rotary member, the arrangement being such that the annular pocket or chamber is divided by the stationary disk or partition into two portions each of which may, if desired, be formed with vanes or blades for the more thorough agitation and rotation of the liquid contained within the pocket-like spaces referred to. This chamber h is in communication with a fixed inlet 2' for the liquid which may be of any suitable form, as for example, the inlet may communicate with an annular or part annular space, is, surrounding or formed in the fixed hollow shaft 7 which space communicates with an apertured boss Z formed integral with or secured to the fixed disk or plate above referred to, the boss providing for the necessary inlet for the liquid into the pocket or chamber 72'. The arrangement is such that the liquid for the annular piston has first to flow into the pocket or chamber it in which during the rotation of the ma chine it rises to a level until it can overflow through an aperture it into the space between the rotary members or into a passage connnimicating therewith, and during the operation of the machine the liquid in the pocket-like space or chamber assumes different levels in the two compartments formed by the fixed plate or disk, dueto the pressure or vacuum produced by. the machine, the annular U-shaped body of liquid thus tormcd serving as a complctelv effective liquid seal or packing for maintaining the pressure or vacuum produccd by the machine. lvleans, such as de scribed in the above-mcntioncd specification. may be provided for maintaining constant the amount of liquid within the machine. A scoop t has been conventionally indicated. This scoop removes the surplus of liquid passing out through ducts s and. thereby keeps the quantity substantially constant.

In one convenient construction the inner member or rotor may be formed of two parts secured together at the requisite distance from one another by studs and distance pieces or may be otherwise suitably formed in such a manner as to leave a central chamber m communicating with the interior of the fixed hollow shaft above referred to, and through a port or ports a with the space between the inner and outer rotary members. lhe threadsat on each half of the rotor' are of course of opposite hand to direct the air or other gas to or from the central plane of the rotor according as the machine is used as a compressor or exhauster.

I prefer also to form the spiral thread thicker at the root than at the tip and form it to present a curved or inclinedface to ward the outlet side of the machine in order to prevent the formation of an annular space at the junction of the thread with the shrouding plate which might serve to trap the air or gas. By this arrangement the force acting on the gas has two components, one in axial, the other in radial direction, which cooperate to readily pass the gas past the said junction.

in any modification of the invention paddles such as a may be fitted between the threads 4 to assist the rotation of the liquid forming the annular liquid piston.

It is to be understood that the invention is not to be confined in its appiication to machines in which the inner member is provided with one or more spiral vanes or threads as it may be employed with equal effect and like advantage in connection with machines in which the inner member is provided with pocket-like receptacles around its outer periphery, or indeed with any other construction of machine of the broad type hereinbefore referred to in the opening paragraphs ofthe specification, and it will be clear that It may suitably modify the details t emes tion is to be applied, providing also the means, if necessary, for maintaining the level of liquid constant within the machine and providing also a liquid seal fed independently with liquid instead of one as de-.

scribed above which is fed by the supply of liquid serving also to form the operative liquid piston of the machine.

Having now described my invention, what I claim as new and desire to secure by Let ters Patent is 1. A rotary compressor or exhauster of the type referred to provided with a fixed inlet or outlet for the gas being operated upon and having a liquid seal independent of and having no direct connection with the operative liquid of the machine and divided into two parts or portions such that there is produced a difference in 'the level of the liquid in the two portions dueto the centrifugal force balancing the vacuum or compression pressure produced by the machine, substantially as described.

2. A machine as claimed in-' claim 1 in which the liquid seal is formed by allowing the operative liquid to enter the machine through a chamber formed in the inner member and divided. into two parts by a plate or diaphragm carried by a fixed shaft upon which the members rotate, substantially as described.

3. In a machine as claimed in claim 1 and having a spiral thread upon its inner member, forming the thread of a greater thickness at the root than at the tip and with one face curved or inclined toward the out let side of the machine, substantially as and for the purpose set forth.

in testimony whereof I have signed my name to this specification.

JUHN JOHNSTON. 

